The present invention relates generally to moving magnetic storage devices and to recording elements incorporated therein, and more particularly to integrated transducer/suspension structures for vertical recording and reproduction which are suitable for batch fabrication and a method for fabrication of the structures.
Moving magnetic storage devices, especially magnetic disk drives, are the memory device of choice. This is due to their expanded non-volatile memory storage capability together with a relatively low cost. Accurate retrieval of the stored information from these devices becomes critical, requiring the magnetic transducer to be positioned as close to the storage media as possible. Optimally, the transducer may actually contact the media.
Magnetic disk drives are information storage devices which utilize at least one rotatable magnetic media disk having concentric data tracks defined for storing data, a read/write transducer for reading the data from or writing the data to the various data tracks, a support means, generally referred to as a slider, for supporting the transducer adjacent the data tracks typically in a flying mode above the storage media, a suspension assembly for resiliently supporting the slider and the transducer over the data tracks, and a positioning actuator coupled to the transducer/slider/suspension combination for moving the transducer across the media to the desired data track and maintaining the transducer over the data track center line during a read or a write operation. The transducer is attached to or is formed integrally with the slider which supports the transducer above the data surface of the storage disk by a cushion of air, referred to as an air bearing, generated by the rotating disk. Alternatively, the transducer may operate in contact with the surface of the disk. The suspension provides desired slider loading and dimensional stability between the slider and an actuator arm which couples the transducer/slider/suspension assembly to the actuator. The suspension is required to maintain the transducer and the slider adjacent the data surface of the disk with as low a loading force as possible. The actuator positions the transducer over the correct track according to the data desired on a read operation or to the correct track for placement of the data during a write operation. The actuator is controlled to position the transducer over the desired data track by shifting the combination assembly across the surface of the disk in a direction generally transverse to the data tracks.
In conventional disk drives, the transducer and the slider are formed separately and then attached to the suspension in a manual, operator controlled precision operation. Typically, these components are extremely small and the positioning of each relative to the other is critical and must be exact. During operation of the disk drive, the transducer must be exactly positioned relative to the data track, which in turn means that the suspension must be exactly positioned onto the slider. The suspension must also provide flexibility to pitch and roll motion for the slider relative to the direction of motion of the rotating disk and yet at the same time provide resistance to yaw motion. Electrical conductor leads connected to the transducer signal input/output terminals are directed along the suspension and connected to an amplifier placed on the suspension or on the actuator. The conductor leads must not add to the spring stiffness of the slider while providing good electrical interconnection. The conductor leads are generally bonded by soldering or ultrasonic bonding, for example, to both the transducer output terminals and the amplifier manually by an operator.
While magnetic recording of information is enormously successful, there is an ever increasing need to improve recording density. In the present state of the art the popular method of magnetic recording has been longitudinal recording. More recently, magnetic recording techniques have turned to considering vertical recording as compared to longitudinal recording as a means for improving the linear density of recorded information. In vertical recording, the magnetic polarity of the recorded bits is oriented vertically or perpendicularly with respect to the recording media surface. The magnetic flux from a recording head write pole-tip passes vertically through the magnetic storage medium, then downstream (or upstream) within the storage disk and back through the magnetic medium to a return pole which forms the flux return path for the magnetic head. The flux return pole has a pole face many times larger than the write pole tip so that the flux passing into the flux return pole is disbursed therealong and hence the flux density is low. Because the density of the flux passing through the recording medium at the return pole is low, there is very little effect by way of reversing or weakening any magnetic patterns in the recording medium downstream of the write pole tip.
As discussed above, the transducer, mounted on a slider, is supported above the relatively moving recording media surface by an air bearing. The performance of magnetic recording systems improve dramatically as the separation between the read/write transducer and the recording medium decreases. Additionally, decreasing the separation between the read/write transducer and the recording medium provides improved track density, the number of data tracks that can be defined on the media surface, as well as the recorded data linear density in an individual data track. However, as the flying height is reduced, the risk of head wear, and in particular, the potential for the transducer to inadvertently contact the disk surface incurring catastrophic wear increases greatly. In recording systems designed to operate with the read/write transducer/slider in contact with the media, the wear may be minimized by the proper selection of both slider and medium surface materials relating to hardness, coefficient of friction, thermal conductivity, etc. The wear between two surfaces in rubbing or sliding contact is also a significant function of the area of contact between the two surfaces and the applied load and inertial forces. While the actual area of contact is significantly less than the area of the surfaces involved, actual contact taking place only at microscopic asperities in the surfaces, reduction of the size and mass of the slider enables a significant red,lotion in the local pressure greatly reducing wear between the surface of the slider and the medium.
To this end there have been disclosed variety of mechanisms which utilize an integrated "REED" approach to fabricating the transducer/slider/suspension assembly. Structured to work in a perpendicular or vertical magnetic recording environment, these devices permit the head and suspension to be easily manufactured having: (i) precise control of component elements utilizing thin film vacuum deposition techniques, (ii) precise formation of air bearings to achieve specified flying heights, (iii) bonding of sliders to suspensions, and, (iv) easy routing of conductor leads.
U.S. Pat. Nos. 5,041,932; 5,073,242; and 5,111,351 entitled "Integrated Magnetic Read/Write Head/Flexure/Conductor Structure" granted to Harold J. Hamilton disclose an integral magnetic transducer/suspension/conductive structure having the form of an elongate dielectric flexure or suspension body with a magnetic read/write transducer embedded within at one end thereof. In a preferred embodiment, Hamilton discloses an elongate, dielectric flexure body of aluminum oxide having a magnetic pole structure and helical coil integrally formed at one end of the flexure body with embedded copper conductor leads running the length of the flexure body to provide electrical connection for the transducer. The integral structure is fabricated utilizing conventional vapor deposition and photolithography techniques. The integral transducer/suspension structure disclosed by Hamilton may be used in a contact recording system or in a system where the transducer flies above the storage medium on a cushion of air.
Contact recording provides greater recording density and achieves higher read signals and greater resolution unregulated by variations in flying height. However, the war associated with prior art contact recording is generally not acceptable. While Hamilton, cited above, discloses an integrated transducer/suspension assembly with greatly reduced mass and size, the disclosed perpendicular head requires fabrication processing in two orthogonal planes which creates processing problems and greatly complicates the manufacturing process.